Question 950603
You have some details wrong, like y-intercept, but your equation is correct.
y=2x-1 passing through the ordered pair (2, -2)
The slope of the perpendicular line is the negative reciprocal, so m=-1/2, x=2, y=-2 
Using slope-intercept form to check:
y=mx+b
-2=-(1/2)2+b
-2=-1 +b
-1=b
Final equation:y=-(1/2)x-1
Slope is -1/2, negative slope drops from left to right.
Y-intercept is b, so y=intercept at (0,-1), one unit below the origin.
X-intercept is at (-2,0)
{{{ graph( 800, 800, -10, 10, -10, 10, -(1/2)x-1) }}}